It went rancid

[chibi-soap]

I made about 80 cakes for Christmas at the beginning of the year thinking that would be clever because it would have time to cure but now it smells horrible, as if the fragrance oil went rancid. One was peppermint and eucalyptus and now it smells like koala poo . Why????

 

[amd]

More than likely not the fragrance oil that went rancid but the oils you used to make the soap - or a poorly formulated soap. If you share your recipe in percentages, including any additives and qty, we can help trouble shoot a better recipe and you can try again for next Christmas. Also, if you used EO's for scent, some don't stick as well as others, so having a nicely scented EO soap after a year cure might be difficult. It varies depending on the EO. Which reminds me... I think some on the forum have had issues with peppermint EO causing problems, I am not one of them.

 

[Nona'sFarm]

What were your ingredients, percentages, and process?

 

[chibi-soap]

Thanks. I'm in the middle of renovations but when I find my notebook I'll post the recipe.

But actually, I used the same recipe last year. The only difference was I used less water so it would take faster. But that wouldn't make it rancid, would it?

Right! I've found the recipe! Unfortunately, I couldn't find the old recipe that didn't go rancid. The only difference is that the old one had a higher water %.
So SF6% water 35%
OO 70% 242g
CO15% 52g
cocoa butter 10% 35g
castor oil 5% 17g

lye 46.5g
Water 122g
3/4tsp each of sugar and salt
3tso fragrance oil

My theory is that since I lowered the water content, I didn't have to stir it as much before trace and therefore the saponification didn't occur throughout the batter.

What do you think?

 

[Obsidian]

Lowering the water didn't cause the soap to go rancid.

In truth, there are so many variables that can cause rancidity its often impossible to figure out the reason.
It could be from the batter being contaminated, to the way it was stored.

Is there any discoloration to the soap at all?

 

[chibi-soap]

Lowering the water didn't cause the soap to go rancid.

In truth, there are so many variables that can cause rancidity its often impossible to figure out the reason.
It could be from the batter being contaminated, to the way it was stored.

Is there any discoloration to the soap at all?

No there was no discoloration. The whole 80 cakes went off, and they were from about 4 different batches! So that would only leave the storage. But they were stored the same as last year It's so strange. I have another cake from the same recipe but with more water from the year before, so about 2 years old, and it is fine! Better than fine!

 

[Obsidian]

I've had some soap get a bad smell like that without any discoloration or other signs of rancidity, just a bad all over smell.
I don't know why, maybe the oil was a bit old or the soap got a bit too warm in storage.

Most everyone who makes soap has to deal with rancid bars at some point. I've tossed my fair share away.
I have learned that high OO, canola and soy are what give me issues so I adjusted my recipe and now my soap rarely goes bad.

How and where are you storing your soap?

 

[DeeAnna]

...My theory is that since I lowered the water content, I didn't have to stir it as much before trace and therefore the saponification didn't occur throughout the batter....

I'm not sure I can buy into this theory. People use anywhere from 25% to 50% lye concentration to make soap, and I've never heard anyone else think less water can trigger rancidity.

The amount of stirring to get to trace might be somewhat related to water content, but if it is true that "saponification didn't occur throughout the batter" you would have seen other problems in this soap right at the time of unmolding -- separation, weeping, lye heaviness on the bottom of the bars, etc. Rancidity would be the least of your worries.

 

[amd]

I have another cake from the same recipe but with more water from the year before, so about 2 years old, and it is fine! Better than fine!

I wonder if this is your problem. The first soap made that is 2 years old was made with fresh/new oils. The newer soap was made from same oils (not same type, but actual same bottles) that had aged +1 year.

 

[chibi-soap]

Thanks everyone. I was rather hoping for a "you silly chook, you should have XYZ" sort of reply. Then I could make my next batch with confidence.
@amd : it did occur to me that I might have used old oils but if I did, it could only have been the castor oil. The rest of the oils we eat if they're not being made into soap. But that is a possibility. Perhaps I had almost a full bottle at the end of the previous years soap making. But even so, to make 80 cakes I would have needed more than one bottle.

Edit: thinking about this, I vaguely remember using up a bottle of argon oil I had for my daughter's hair. Maybe that plus some old castor oil did the damage. Hmm....I am going to go with this theory and make sure I use fresh oils every time from now on.

@Obsidian : I stored them sitting vertically in a fruit tray; the sort of box that peaches etc. come in, with baking paper in the bottom and a muslin cloth over the top. Plenty of ventilation, I would have thought. They were in our study the whole time.

 

[lucycat]

Did you use the same fragrance amounts for both soaps? Personally I don't find Eucalyptus EO particularly attractive and it can overtake the blend if it is dominant.

 

[penelopejane]

Thanks everyone. I was rather hoping for a "you silly chook, you should have XYZ" sort of reply. Then I could make my next batch with confidence.
@amd : it did occur to me that I might have used old oils but if I did, it could only have been the castor oil. The rest of the oils we eat if they're not being made into soap. But that is a possibility. Perhaps I had almost a full bottle at the end of the previous years soap making. But even so, to make 80 cakes I would have needed more than one bottle.

Edit: thinking about this, I vaguely remember using up a bottle of argon oil I had for my daughter's hair. Maybe that plus some old castor oil did the damage. Hmm....I am going to go with this theory and make sure I use fresh oils every time from now on.

I bought a new bottle of jojoba oil and every soap I made with it (even if it was around 1%) went bad. I figure the soap store hadn’t stored it properly or it was older than the use by date suggested.

I’d suspect the argon oil if I were you. So very disappointing but at least you have time to make more before Christmas.

 

[chibi-soap]

Thank you, everyone. I'm going to throw away the fragrance oils and castor oil I have (although it looks unopened, but it must be old).
I've ordered enough fragrance oil to make exactly 60 cakes, so there will be no leftovers tempting me to use them, and I'll buy all new oil once the fragrances arrive and have a big soap bash! Fingers crossed it works this year!

Thank you again for all your help.

BTW - if people are interested, the recipe I posted above works really well on hair!

 

[gorio]

you silly chook - the answer is simple however the explanation may not be
First let me tell you off for not knowing if your making soap products you should!
Then let me dress down all the soap makers who have never told you it is one of the first things you should be taught before you step in front of your chemistry lab. Yes that's right making soap is chemistry involving dangerous chemicals.
Just following someones recipe is not making soap.
Now all chastising done to your problem - so what is soap, no not the easy answer the real answer, it is long chains of fatty acids, characterised by the chemical structure of those fatty acids, which are all different - told you the explanation was tough. Your answer shortly
Long chains of 10-18 carbons are made for soaping the longer the harder the soap. -
That's the gloss over bit done (but hope you didn't)
Now saturated fats are saturated with hydrogen and the important thing is there are no "Double bonds"
Whilst non saturated fats are liquid at room temperature and have one or more double bonds
ANSWER (at last)
The more double bonds the more the chance of your soap going rancid
now soapee and soap calc (yes its back) have a section for these (ever wondered why it was there)
ones to watch for are ricinileic/oleic/linuleic/ and worse linolenic
18:1, 18:1 18:2 18:3 respectively. That is to say 18 carbon to 3 double bonds
minimise linolenic to 5% of recipe

so double bonds is your problem

 

[shunt2011]

you silly chook - the answer is simple however the explanation may not be
First let me tell you off for not knowing if your making soap products you should!
Then let me dress down all the soap makers who have never told you it is one of the first things you should be taught before you step in front of your chemistry lab. Yes that's right making soap is chemistry involving dangerous chemicals.
Just following someones recipe is not making soap.
Now all chastising done to your problem - so what is soap, no not the easy answer the real answer, it is long chains of fatty acids, characterised by the chemical structure of those fatty acids, which are all different - told you the explanation was tough. Your answer shortly
Long chains of 10-18 carbons are made for soaping the longer the harder the soap. -
That's the gloss over bit done (but hope you didn't)
Now saturated fats are saturated with hydrogen and the important thing is there are no "Double bonds"
Whilst non saturated fats are liquid at room temperature and have one or more double bonds
ANSWER (at last)
The more double bonds the more the chance of your soap going rancid
now soapee and soap calc (yes its back) have a section for these (ever wondered why it was there)
ones to watch for are ricinileic/oleic/linuleic/ and worse linolenic
18:1, 18:1 18:2 18:3 respectively. That is to say 18 carbon to 3 double bonds
minimise linolenic to 5% of recipe

so double bonds is your problem

There is absolutely nothing wrong with the recipe as posted. Not sure what you are talking about. This issue as others stated was likely old/rancid oils. Also, you are making quite an assumption as to if they are using someone else's recipe. And even if they are it's still making soap. That or I must be an idiot since I followed someone else's recipe when I first started and there are likely many who are still using a recipe they found somewhere like here. There is nothing wrong with it. However, didn't read that at all. They were looking for their recipe. And it's not rocket science as you seem to infer. Yes, there is a bit of science involved and some safety required, but most soapmaker's aren't scientists nor do they want to be. Also, the OP had made other soaps, hence looking for their other recipe.

So please think carefully before making assumptions or chastising.

Since you're new here please go to the introduction forum and introduce yourself and tell us a bit about you and your soapmaking experience.

Also, be sure to read the forum rules.
Welcome to the forum.

 

[Saffron]

Hi Chibi-soap,
Have you tried using the soap yet?

I made a batch of Castile (with 5% Castor oil) about 2 years ago and kept a few bars aside, wrapped in paper and away from light and heat, to see how it would age over time. About three weeks ago I unwrapped a bar and upon examination it had developed a small DOS, although the other bars were fine, and smelled a bit rancid. I decided to use it anyway in order to determine whether the long cure had any effect in reducing the dreaded slime usually associated with castile soaps. To begin with, the rancid smell was not very pleasant, but there was no slime. Hooray! After about a week or so of use, there was no rancid smell and the soap was fine. Hooray again! Could it be that only the top layer of the soap which had been exposed to air had gone rancid but the inner part of the soap was fine? Great! However, not so great news about the slime, it appeared with a vengeance with repeated use and the bar got very soft towards the end – almost mush ☹

So, I would say try your soap for a week and see how it smells after the top layer has been washed off.

 

[bakmthiscl]

DON'T THROW AWAY RANCID SOAP!

 

[shunt2011]

DON'T THROW AWAY RANCID SOAP!

Why? I throw it away, who wants to use smelly stinky soap? Seriously? If it's only a few spots I've dug them out and used it. If a soap is totally rancid into the garbage it goes. No question.

 

[bakmthiscl]

Sorry for shouting and also for 2 messages -- some keyboard shortcut bit me in the ...
Anyway, Don't throw away rancid soap, especially when soap is our best single defense from the novel Corona virus.
Rancid OIL (or fatty acid, more likely) stinks. Rancid SOAP, not so much. If your soap smells strongly rancid, you probably have residual oil that went rancid; it may or may not have saponified first.
The difference between fatty acids and soap is not much: the former is the free acid (e.g., palmitic acid), the latter the sodium (or sometimes potassium) salt (e.g., sodium palmitate).
You can SALVAGE that soap. It may never be as wonderful as you intended, but it will be usable soap, which is my point.

Here's one way, which you should try in small scale before scaling up to the whole lot:

1. Weight the soap you're going to rework. This datum will be needed later.
   
2. Cut or grate the soap into small pieces. (Optional, but it speed the process a lot.)
3. Soak the pieces in an excess of DISTILLED or DEIONIZED water (in a extra-large glass or SS vessel). Record the total volume of water you use, throughout these several steps. This datum will be needed later. Do not use tap water. If you run a dehumidifier, the condensate from this is fine. The morning dew would also be fine if you have a poetic streak and the infinite patience needed to collect it in quantity. If you have a salt-based water softener, and keep it in good operating condition (purging the unit and recharging with salt as per the instructions from the manufacturer) that water would also do -- It's not deionized, but the primary residual cation is sodium, which is acceptable.
   
4. When the pieces of soap are sufficiently soft (heating helps, but avoid boiling to avoid foaming) mix to dissolve the soap into the water, adding more water (see #3) if necessary, as it likely will be. Stir gently to minimize foaming (which will occur regardless).
   
5. To convert residual (rancid) fatty acids to soap, add more lye. You'll have to determine the quantity of lye (sodium hydroxide = NaOH) from what you know about the batch. For example, if you make your soap like I do with 5% excess oil, and you're reworking 1 kg of soap, then you have approximately 50 g of excess unsaponified fatty acids present. You need enough lye to completely saponify these fatty acids, with some excess. Feel free to overestimate (slightly) as the excess lye will come out in the wash (literally). For example, you may assume you have only C18 fatty acids present. The MW of these is roughly 284g/mole, so 50 g is 176 mmole (=0.176 mole). So you need at least 176 mmole of lye, MW 40 g/mole. 176 mmole x 40 g/mole = 7 grams lye, minimum.
6. Let the mix stew for a while at 120-150F (50-65C), avoiding boiling to minimize foaming. The mix will foam somewhat anyway. Add enough water to keep the foam under control. (This is why you need a large vessel.) If you worry you may not have added sufficient lye, you may use any usual test for free lye (such as taste). When adding water, bear in mind that the more water you use, the more salt you will need to use later and the more soap you will lose, dissolved in the brine.
   
7. Now you need to add enough salt (sodium chloride = NaCl) to precipitate the soap. (Soap is relatively insoluble in brine.) 36 g of NaCl will saturate 100 g water. A roughly half-saturated final concentration will probably do, so add 180 g NaCl per liter of water you used. You can use any clean salt for this. I use salt intended for water softeners because it is clean, but I grind it in a mortar so it will dissolve faster, as it comes in lumps. Add the salt slowly, with stirring, as it may happen that you can get away with using less salt, a good thing. As the salt dissolves, the soap will precipitate -- but it likely will float due to entrained air. Stir till the precipitation is complete, then ladle off the soap into a colander or cheese cloth to drain.*
8. Transfer to your mold and cure the soap as if it were a new batch. You should find that the odor has diminished greatly, but there's no guarantee that it will be suitable for milady's boudoir. If you want to add scent to it, which I never do, I think you should do so just before you place it in your mold.

*The soapy brine can be discarded, or used to wash dishes. I wouldn't use it to wash clothes or hands.

 

[shunt2011]

I disagree with your statement. I've had 100% CO soap with a negative SF go rancid and it was stinky and gross. Sorry, been making soap a long time. And A few bars of soap in the garbage is not going to affect a darn thing with the Corona virus. I'm also, not going to waste my time and supplies to try to save some smelly soap.